scsi: ufs: Customize flush threshold for WriteBooster

Allow flush threshold for WriteBooster to be customizable by vendors. To
achieve this, make the value a variable in struct ufs_hba_variant_params.

Also introduce UFS_WB_BUF_REMAIN_PERCENT() macro to provide a more flexible
way to specify WriteBooster available buffer values.

Link: https://lore.kernel.org/r/20200509093716.21010-4-stanley.chu@mediatek.comReviewed-by: Asutosh Das <asutoshd@codeaurora.org>
Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/ufs/ufs.h

@@ -478,10 +478,7 @@ enum ufs_dev_pwr_mode {
 	UFS_POWERDOWN_PWR_MODE	= 3,
 };
 
-enum ufs_dev_wb_buf_avail_size {
-	UFS_WB_10_PERCENT_BUF_REMAIN = 0x1,
-	UFS_WB_40_PERCENT_BUF_REMAIN = 0x4,
-};
+#define UFS_WB_BUF_REMAIN_PERCENT(val) ((val) / 10)
 
 /**
  * struct utp_cmd_rsp - Response UPIU structure

drivers/scsi/ufs/ufshcd.c

@@ -5301,8 +5301,8 @@ static bool ufshcd_wb_presrv_usrspc_keep_vcc_on(struct ufs_hba *hba,
 			 cur_buf);
 		return false;
 	}
-	/* Let it continue to flush when >60% full */
-	if (avail_buf < UFS_WB_40_PERCENT_BUF_REMAIN)
+	/* Let it continue to flush when available buffer exceeds threshold */
+	if (avail_buf < hba->vps->wb_flush_threshold)
 		return true;
 
 	return false;
@@ -5336,7 +5336,7 @@ static bool ufshcd_wb_keep_vcc_on(struct ufs_hba *hba)
 	}
 
 	if (!hba->dev_info.b_presrv_uspc_en) {
-		if (avail_buf <= UFS_WB_10_PERCENT_BUF_REMAIN)
+		if (avail_buf <= UFS_WB_BUF_REMAIN_PERCENT(10))
 			return true;
 		return false;
 	}
@@ -7462,6 +7462,7 @@ static const struct attribute_group *ufshcd_driver_groups[] = {
 
 static struct ufs_hba_variant_params ufs_hba_vps = {
 	.hba_enable_delay_us		= 1000,
+	.wb_flush_threshold		= UFS_WB_BUF_REMAIN_PERCENT(40),
 	.devfreq_profile.polling_ms	= 100,
 	.devfreq_profile.target		= ufshcd_devfreq_target,
 	.devfreq_profile.get_dev_status	= ufshcd_devfreq_get_dev_status,

drivers/scsi/ufs/ufshcd.h

@@ -570,6 +570,7 @@ struct ufs_hba_variant_params {
 	struct devfreq_dev_profile devfreq_profile;
 	struct devfreq_simple_ondemand_data ondemand_data;
 	u16 hba_enable_delay_us;
+	u32 wb_flush_threshold;
 };
 
 /**